Bonjour,

1) f(x) = base + 50x

on sait que : f(10) = 1700

⇒ base + 50x10 = 1700 ⇒ base = 1700 - 500 = 1200

Donc : f(x) = 1200 + 50x

2) g(x) = 710 + 120x

3) f(x) = g(x)

⇔ 1200 + 50x = 710 + 120x

⇔ 120x - 50x = 1200 - 710

⇔ 70x = 490

⇔ x = 490/70 = 49/7 = 7

Le salaire vaut alors :

f(7) = 1200 + 50x7 = 1200 + 350 = 1550 €

ou

g(7) = 710 + 120x7 = 710 + 840 = 1550 €